Wireless circuits



June 6, 1933. c. E. G. BAILEY 1,912,617

WIRELESS CIRCUITS Filed Feb. 25, 1930 INVEN 70R AT TOR/V575.

l at entecl june 6,. H533 UNITED STATES CHRISTOPHER EDMUND eEEvAs BAILEY; oriionno1vfmemivn,.,AssIGuon iro vIoTo TALKING MACHINE COMPANY; AoomaoEATIoN on NEW JERSEY WIRELESS c cUITs,

Application filed February 25, 1930, Serial No.

I ing circuits, which comprise two or more iected by the operation of one control. A

tuned circuits. p In such circuits it is desirable that the tuning of the tuned circuits should be efdifliculty is experienced in adapting such a single-controlled circuit for use with aerial systems of difierent capacity, owingto the capacity to earth of the aerial shunting the inductance included in one of the tuned circuits.

An object of the present inventionis to provide means whereby the efiiect of the capa'city to earth of the aerial in one tuned circuit, is compensated for in another tuned circuit thus allowing the tuning of the circuits to be eifected by the operation of one control.

According to the present invention this is carried intoiefiect by providing acondenser shunted across a portion only of the inductance in one tuned circuit, a portion only of the inductance in the other tuned circuit being includedin the circuit between the aerial and the earth. The inductance of each of these said portions may, with advantage, be made equal. Also,-the compensating condenser may be variable so as to admit of its being adjusted when aerials of difierent capacity to earth are used.

of the first valve 3, which acts as a high-lire The invention is illustratedin theiaccompanying drawing by way of example as applied to a wireless receiver embodying one stage of high frequency amplification and a detector.

One tuned circuit comprises an aerial tuning inductance 1 having a variable condenser 2 connected in parallel therewith. One end of this inductance is connected to the grid quencyaniplifier and is of the screen grid type, the other end being earthed. The aerial 4 is connected to a tapping point 5 on the inductance 1, situated at a distance from the earthed end approximately equal to one quarter of thetotal length of the inductance. The second tuned circuit, which serves as a coupling between the first valve 3 and a sec- 431367, and in Great Britain March 7 1929 a variable tuning condenser *8 connected in 3 parallel therewith, one'endof this inductancebeingconnectedthrough a condenser 9, tothe anode of the first valve 3 and, througlra condenser 10, to the grid of the second valve 6,the other end oftheinduct'ance 7 being connectedto earth and to the filaments of the two valves. The anode of the valve 3 is "connected through a high frequencychoke coil 11 to the positive terminal of'a high tension source, the negative terminal of which is earthed. The screen grid oi -the valve 3 is also connected to asuitable point o'nthis source. A variable condenser 12 which acts as a compensator is tapped across a portion of the second inductance? the inductance'ofthis portion equalling that of the portionNofthe aerial tuning inductance 1 shunted by the capacity to earth of the aerialt. 'Thecapacity ofthe condenser 12yis madeequal to this capacity to earth oftheaerial, and remains fixed at this value.

The two tuningfcondensers 2 and 8 are me chanically interconnected, or ganged, so that tuning can be efiected by the operation of one controLv i I i The anodecircuit of the valve G-may be connected inanyknown or suitable manner toaireproducirigdevice or to alow frequency amplifier. p I

The invention can clearly be applied to circuits comprising more than two tuned circuits, such, for example, as a multi-stage high frequency amplifier, in whichcase the effect of the capacity between the earth and the aerial, which capacity is in shunt with a portion of the inductance in one tuned circuit, may be separately compensated for in each of the other tuned circuits in the manner described'above. V

I claim I 1. A wireless circuit comprising two tunable oscillatory circuits wherein a portion only of the inductance in one of said tun- .able circuits is included in the circuit between the aerial and earth terminals, charshunted across a portion only of the inductance in the other tuned circuit.

2. A Wireless circuit according to claim 1, characterized by the fact that said portions are substantially equal.

3. A wireless circuit according to claim 1, characterized by the fact that the said condenser is a variable condenser.

4. A Wireless circuit according to claim 1, characterized by the fact that the tuning controls for said tunable circuits are interconnected.

5. In a signal amplifying system, a plurality of tunable circuits, means for simultaneously tuning said circuits and variable means connected directly in shunt to a portion of one of said circuits for compensating the detuning of another of said circuits by the connection thereto of an antenna.

6. In a signal amplifying system, a thermionic device having an input inductor, means for connecting spaced apart points on the inductor respectively to an antenna and to a counter-capacity, an output inductor connected to said device,said inductor also serving'as an input inductor for a succeeding thermionic device, meansfor simultaneously tuning said inductors, and means associated with the output inductor for compensating for the electrical characteristics 1 of an antenna, said means including a variable impedance device connected directly in shunt to a portion of the output inductor, whereby true unicontrol may be'had irrespective of the connection to the input inductor of differing antennae.

7. In a signal amplifying system, a plurality of tunable circuits, atuning inductance in each of said circuits, means for simultaneously tuning said circuits, and vari able means connected directlyinshunt toa portion of'the tuning inductance of one of said circuits for compensating the detuning of another of said circuits by connection thereto of a signal input circuit.

In testimony whereof I havesigned my name to this specification.

CHRISTOPHER EDMUND GERVASE BAILEY. 

